MORPHOLOGY:
The average body mass for both the male and female brown titi is about 1 kilogram. The canines are sexually monomorphic for this species (Kinzey, 1972). The dental formula is 2:1:3:3 on both the upper and lower jaws (Ankel-Simons, 2000). The tail of the brown titi is not prehensile. This species has a pelage coloration that is blackish on the forehead, forearms, legs, and two-thirds of the tail, but the tip of the tail is pale in color (Hershkovitz, 1990; Aquino and Encarnacion, 1994). The sideburns are reddish brown or blackish and the dorsal side and the sides of the body are brownish agouti in coloration (Hershkovitz, 1990; Aquino and Encarnacion, 1994). The ventral side is brownish or reddish-brown in color (Hershkovitz, 1990; Aquino and Encarnacion, 1994).

RANGE:
The brown titi is found in the countries of Bolivia, Brazil, and Peru and is found to live in bamboo forests (Kinzey, 1997; Cameron and Buchanan-Smith, 1991-1992). This species is found from the middle and upper Rio Madeira basin in Rondonia and Acre, Brazil, and in the departments of Madre de Dios , Puno, and Cusco, Peru (Hershkovitz, 1990). Range also extends west into the upper Rio Purus basin in Amazonas, Brazil and Ucayali, Peru (Hershkovitz, 1990). This species is also found in the forests of the north-western part of the department of Pando, Bolivia (Cameron and Buchanan-Smith, 1991-1992). The brown titi is found in altitudes ranging from 100 to 650 meters above sea level (Hershkovitz, 1990). This species also lives in forest edges, swamp edges, and areas around tree falls (Kinzey, 1981). In Peru this species prefers to live in riverine vegetation and in pacales (associations of Guadua spp. trees) (Aquino and Encarnacion, 1994). The brown titi is found in Manu National Park in Peru and Guajara-Mirim Stae Park, Rondonia, Brazil (Kinzey, 1981; Ferrari et al., 1995).

ECOLOGY:
The brown titi is primarily a frugivorous species, but also eats leaves and insects. In Manu National Park, fruit accounts for 47% of food consumed with Brosimum rubescens and Ficus sp. being the most important fruits consumed (Kinzey, 1981). Other important fruit species consumed at Manu National Park were: Maytenus magnifolia, Phaseolus sp., Pourouma cecropiaefolia, and Paulliniasp. (Kinzey, 1981). Crandlemire-Sacco (1988) found that the fruit species Iryanthera juruensis made up one-fourth of the total fruit eaten for this species in southeastern Peru. Fruits consumed by the brown titi tend to be soft (Kinzey, 1981). Foraging for fruit is mainly done in small-crowned fruit trees (Wright, 1984, 1986). Both mature and immature leaves are consumed as well as new growth at the tips of lianas (Kinzey, 1978). The brown titi obtains most of its protein from leaves (Kinzey, 1978). The invertebrates consumed by this species include both solitary and communal spiders, larval and adult lepidopterans (moths and butterflies), and hymenopterans (Crandlemire-Sacco, 1988). Lactating females had a greater success rate at catching insects than fathers carrying infants during the time when insects are most abundant in October and November (Wright, 1984). This species also eats seeds (Wright, 1985). During the dry season when fruit is not as abundant, the brown titi forages on bamboo leaves and vine leaves (Wright, 1985, 1994). Family groups will feed in the same tree at the same time (Kinzey et al., 1977; cited in Kinzey, 1981). This species has feeding peaks early in the morning after they wake up and in the mid afternoon, with a rest for about an hour around the mid-day (Kinzey, 1978). Females often lead the group when foraging, especially when they are lactating (Wright, 1984). The resources used for feeding by this species are small, predictable, and evenly spaced throughout the home range (Wright, 1986). The primate species Cebus apella, Cebus albifrons, and Ateles paniscus will displace the brown titi from feeding trees (Wright, 1994).

This species is sympatric with Saguinus fuscicollis, and they reduce competition with each other by foraging for different plant and animal species (Crandlemire-Sacco, 1988). Group sizes in Manu National Park, Peru, range from 2 to 4 individuals (Kinzey, 1981). In the state of Rondonia, Brazil, the mean group size was found to be 2.25 individuals (Ferrari et al., 2000). This species is diurnal and arboreal and rarely comes to the forest floor (Kinzey, 1997). This species sleeps in dense vines so as to be concealed (Wright, 1985). In Manu National Park this species sleeps in trees located in vegetation with a large number of palms, lianas, and dense undergrowth (Kinzey, 1981). This species was also found to sleep in emergent trees provided with tangles of vines (Aquino and Encarnacion, 1994). The brown titi spends most of its time in the understory, spending 48% of the time there (Kinzey, 1981). Most of the activities of this species occur in the lower and middle levels of the forest (Aquino and Encarnacion, 1994; Ferrari et al., 2000). In the winter months (June, July, and August), the brown titi will become active four hours later than in the summertime (Wright, 1994). The day range for this species is less than 700 meters per day (Kinzey, 1978). Members of the group will travel and feed in close proximity (Wright, 1986). The day of path of this species tends to be shorter as compared to other primate species (Wright, 1994). The brown titi is preyed upon by the harpy eagle, Harpia harpyja, and the crested eagle, Morphnus guianensis (Wright, 1994).

LOCOMOTION:
The brown titi moves through the understory of the forest quadrupedally as well as by leaping (Fleagle, 1988; Lawler et al., 1996). This species often uses vertical clinging when feeding (Fleagle, 1988). The brown titi tends to use small supports, those between 2-5 centimeters, when moving through the forest (Crandlemire-Sacco, 1988). The supports used also tended to be horizontal rather than vertical or oblique (Crandlemire-Sacco, 1988).

SOCIAL BEHAVIOR:
The brown titi has a monogamous mating system and mates for life. A dominance hierarchy does not seem to exist (Kinzey, 1997). The basic group is composed of the breeding pair and their offspring. Grooming is an important activity that serves to strengthen social bonds amongst members of the group. The males participate in caring for the infants. This species, like members of its genus, is highly territorial (Kinzey, 1997). Pairs of brown titis have been know to engage in duets with other pairs at dawn (Fleagle, 1988; Wright, 1984).

The father is the primary carrier of the infant from the first weeks in the brown titi (Wright, 1984, 1986, 1994). The infant started to become independent by the fourth week but was still carried by the father (Wright, 1984). The infant only returns to the mother to suckle (Wright, 1984). At three weeks the father carried the infant for 92% of the time, by two months of age the father carried the infant for 57% of the time, at three months the infant was carried for 38% of the time, and by four months the infant was carried for 1% of the time by the father (Wright, 1984, 1986). At three months the infant would usually leap on to the father's back only when disturbed (Wright, 1984). At four months the father only allowed the infant to ride on the back when chased by large monkeys, such as Cebus apella (Wright, 1984). During the first month of nursing the mother would initiate suckling bouts, pulling the infant from the father towards her (Wright, 1984). The mother nursed the infant four to five times a day until the infant was eight months old, with each suckling bout lasting on average 3 minutes (Wright, 1984). The mother would lick and clean the genitalia of the infant for the first two months while nursing (Wright, 1984). After nursing, the mother would return the infant to the father and move away (Wright, 1984). When the infant is two months of age the mother will call for the male to bring the infant towards her because she usually feeds 25-50 meters ahead of the father and the infant (Wright, 1984). At this time the infant left the father on its own to go to the mother to suckle (Wright, 1984). By the third month, the infant would actively seek out the mother to nurse (Wright, 1984). Suckling was less frequent from the seventh to eighth months because of weaning conflicts between the infant and mother (Wright, 1984, 1994). The father actively shares food with the infant from the time the infant is 2 months to 1 year old (Wright, 1984). The mother does not share food with the infant because she needs all the food she can consume for milk production (Wright, 1984). The father was main individual who plays with the infant and also plays with older juveniles (Wright, 1984). Mothers will rarely play with the infant, with bouts occurring between the infant and mother only 9% of the time (Wright, 1984). The mothers were the main participants in social grooming, grooming the infants more than the fathers (Wright, 1984). Fathers carry the infants rather than the females because of the energy demand to the female because of lactation and also related to this is the energy demand of fleeing predators is less on the father because he is not lactating (Wright, 1984). Fathers will also participate more in parental care because they are assured of the paternity of their infant because they have a monogamous mating system (Wright, 1986).

This species forms mixed-species associations with Saguinus fuscicollis and Saguinus imperator (Aquino and Encarnacion, 1994). Mixed-species associations between brown titis and Saguinus fuscicollis are short, lasting usually only an hour (Crandlemire-Sacco, 1988). This species and Saguinus fuscicollis differ in diet making mixed-species associations possible, with Saguinus fuscicollis consuming more fruits and more insect prey than the brown titi (Crandlemire-Sacco, 1988). Saguinus fuscicollis tends to prefer orthopterans (grasshoppers) as invertebrate prey, where this species prefers lepidopterans, arachnids, and hymenopterans (Crandlemire-Sacco, 1988). The brown titi also uses more smaller supports in the forest, so competition between it and Saguinus fuscicollis is reduced, thus mixed-species associations would not have a negative effect on either species; the two species occupy different niches in the forest (Crandlemire-Sacco, 1988).

VOCAL BEHAVIOR:loud call: This call is composed of a series of short sequences of noises that sound like "chirrup-pump". This call is given by males as a territorial call and can be heard for up to one kilometer. This call is described as being "turkeylike" (Kinzey, 1981; cited in Wright, 1994). The call is emitted by the male and female pair together in the early morning (Kinzey, 1981; cited in Wright, 1994).

OLFACTORY COMMUNICATION:

VISUAL COMMUNICATION:

TACTILE COMMUNICATION:tail-entwining: This is used to reinforce bonds amongst pairs. This is where two individuals are sitting and have their tails wrapped around each others.

social grooming: This is when one individual removes dead skin and parasites from another individual. This behavior is used to reinforce social bonds. This behavior is common during rest periods and before going to sleep (Wright, 1994).

REPRODUCTION:
The brown titi gives birth to a single offspring per year (Aquino and Encarnacion, 1994). The majority of births of this species occur between October and February (Aquino and Encarnacion, 1994).